Trichoderma virens as a biocontrol of Toxocara canis: In vivo evaluation.

BACKGROUND: Microorganisms have been widely studied as biological control agents of parasites of medical and veterinary importance. Coprophagous arthropods, bacteria and fungi are among the different organisms evaluated as potential biological control agents. Nematophagous fungi capture and digest the free forms of nematodes in the soil. Due to its zoonotic potential, Toxocara canis have been brought to the attention of researchers. AIMS: The aim of the present study was to determine whether the administration of embryonated T. canis eggs exposed to the nematophagous fungus Trichoderma virens reduces parasite infection in experimental animals. METHODS: Embryonated T. canis eggs were exposed to T. virens mycelium for 15 days at 25°C. Subsequently, 100 fungus-exposed eggs were orally administered to 20 Swiss mice. As a positive control, another 20 mice received 100 embryonated eggs that were not exposed to the fungus. After 48h, the animals were killed, and heart, lungs and liver were harvested for the recovery of larvae. RESULTS: The organs of the animals that received embryonated T. canis eggs exposed to the fungus showed a lower mean larval recovery when compared with the animals that received embryonated eggs without fungus exposure (p<0.05). CONCLUSIONS: The exposure of T. canis eggs to T. virens reduces the experimental infection, demonstrating the potential of this nematophagous fungus as a biocontrol agent.

Effect of Paecilomyces lilacinus, Trichoderma harzianum and Trichoderma virens fungal extracts on the hatchability of Ancylostoma eggs.

BACKGROUND: Ancylostoma species have demanded attention due to their zoonotic potential. The use of anthelmintics is the usual method to prevent environmental contamination by Ancylostoma eggs and larvae. Nematophagous fungi have been widely used in their biological control due to the fungus ability to capture and digest free nematode forms. AIMS: The aim of this study was to evaluate the effect of four different fungal extracts of Paecilomyces lilacinus (n=2), Trichoderma harzianum (n=1) and Trichoderma virens (n=1) isolates on the hatchability of Ancylostoma eggs. METHODS: Fungal extracts consisted of fungal broth culture supernatant without filtration (crude extract) and filtered broth (filtered extract), macerated mycelium (crude macerate), and macerated mycelium submitted to filtration (filtered macerate). The Ancylostoma eggs were obtained from the feces of naturally infected dogs. In vitro assays were performed in five replicates and consisted of four treatments and one control group. RESULTS: The activity of the fungal extracts of each evaluated fungus differed (p<0.05) from those of the control group, showing significant ovicidal activity. The hatching of the eggs suffered reduction percentages of 68.43% and 47.05% with P. lilacinus, and 56.43% with T. harzianum, when crude macerate extract was used. The reduction with the macerate extract of T. virens was slightly lower (52.25%) than that for the filtered macerate (53.64%). CONCLUSIONS: The results showed that all extracts were effective in reducing the hatchability of Ancylostoma eggs. The ovicidal effect observed is likely to have been caused by the action of hydrolytic enzymes secreted by the fungi.